Math · NUMORA
Sample Size Calculator
n = z²p(1−p)/E².
Open interactive calculatorHow to use
Sample size for a proportion. z is 1.96 or 1.645.
Formula
n = z² p (1-p) / E²
FAQ
Is this Sample Size calculator accurate?
The formula and assumptions are shown on the page, and the engine is covered by audit tests. Results are for reference — not financial or medical advice.
Do I need an account?
No. Calculations run in your browser. Recents can stay on this device.
What inputs do I need?
Sample size for a proportion. z is 1.96 or 1.645.
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